Carter, Iturra, Lenox, Starrett Comparison

[Mike Cutler]

I said that I would not post again on this subject. So much for that.

Actually Ken, I was hoping that you would post again on the subject.

[Mark Duginske]

This is the discussion I was hoping to generate.

I will try to address some of the questions but first I would like to make a comment particularly to Mike C. and Ken G. because you guys are more technical than I am. The article did not address the issue of the discrepancies between the gauges because that is a whole another issue. I wondered about the discrepancies and speculated on it but Aaron S (in a phone conversation) and Ken G. corrected me which is good.

Mike C. Thanks for participating. Also thank you for your email address. I will contact you before we do more testing. I appreciate your input and your willingness to participate in this discussion.

I had mixed emotions about giving out the numbers because it is possible that there is something wrong with one of the gauges. Perhaps I should get another Iturra gauge. However, I have two Lennox gauges (one is new and the other is 18 years old) and they both read exactly the same every time. If all of the gauges had the same results we would not be having this discussion. We want to do more testing and I’m open to suggestions. Aaron and I talked about buiding a framework from which we could hang a piece of blade which could hold the gauges. On the bottom of the blade
we would make something that would hold a weight. That way we could exactly duplicate the amount of weight for each test. What do you guys think of that? Should we do something different?

Aaron and I have talked about having a conference where we would do various test and demonstrations. Unfortunately there is not a lot of usable testing or research being done.

We are going to be working with an electrical engineer to do a number of test. We are open to suggestions. At this point I have more questions than answers.


Thanks,

Mark Duginske

[Mark Duginske]

Ken: I went to the text file for the new book and copied this.

Silicon Steel Blades

One variation of the carbon steel blade is blade stock from Sweden which has a high silicon content. Silicon steel blades have a carbon content similar to C1074 spring steel. That is, it's carbon content ranges from .74-.79%. It's silicon (Si) content is high at around 1.5% whereas regular carbon steel has a silicon (Si) content of .16-.19%. The reason for high silicon content is its ability to tolerate heat. It is appropriately named "Friction" band and is used primarily for “friction sawing” when cutting metal at speeds of around 6,000-14,000 feet per minute. This technique is used to cut through different types of steel and compound materials. The material being cut is heated by the cutting action of the blades and softens in front of the cut. Even though the blade is not designed for woodworking it is aggressively marketed at a premium price. These blades have teeth in the 60 Rc range with a 30 Rc body. They are initially sharp and cut well in the beginning, but I don’t think that they are as durable as a high quality carbon steel blade. These blades are advertised as requiring less tension but there is not a good technical explanation for using less tension than usual.

Note to Ken G.
I was told by someone in the blade business that these blades have a tendency to stretch if too much tension is applied. I can not confirm that but that is one of the things I would like to test.

[Jim Dailey]

Mark,

When it comes time for testing if you'd like another Iturra gauge... you can can use mine.

Just send a PM & I'll send you my email address.

jim

[lou sansone]

Some how I feel that the discussion of blade tension gages is not complete without a sound engineering reason for using them. I did explore this issue in a previous post. In my mind there are a couple of things going on with the band saw blade and a couple of reasons for trying to measure the tension.
From my previous post

" it turns out that many steels tend to yield at about 1/3 of 1% strain. so it looks like band saw blade mfgs simply play it real safe with the blade tension in the 15kpsi to 30kpsi range ( 1/20 to 1/10 of 1% strain ). this gives the blade a decent amount of tension, but pretty far away from actually yielding the steel for plastic deformation. "

the other issue is related to harmonic vibrations and a standing wave on the taught steel band. I seems to me that the flutter test is trying to get to this issue.

any thoughts ?
Lou

[Mark Duginske]

Response to Wilbur Pan

“does increasing tension result in a better cut, or is it unnecessary”
Not necessarily, the analogy that I use for the band saw is that it is like a soup, there are a number of ingredients and they have to work together. Tension is one important ingredient but more is not necessarily better (like salt). If too much tension is applied the spring will compress completely and the shock absorber function is lost. The top wheel hinge will bend or break as shown in the photo in the article, or the wheels twist or are pulled out of alignment. There is a wide range of “functional tension”. On my 14” saw I can resaw with a sharp 1/2” blade with the saw set at the 1/4” mark although I usually use the 1/2” mark. As the blade dulls I move it to the 3/4” mark. A lot of the tension requirements depends on blade choice and sharpness. Ultimately, with or without a gauge you should experiment a little bit to find the sweet spot.

If I remember correctly Walker Turner was bought by Delta in 1953. They are very nice band saws. For tensioning I would not recommend the clamp on gauges. There is a thread now on using the dial caliper to measure the amount of blade stretch and that makes sense if that appeals to you. That is one option. The other option is the flutter method but I would give it more than one turn. The other method is just to experiment. As I said in another thread there is the misconception that the “correct” tension is a very narrow band like between one 49 yard line and the other 49 yard line. It is more like the middle of the field with quite a wide area of acceptable tension settings.

I think that a lot of using the clamp on gauge has to do with the “placebo affect”. I took a pill 30 minutes ago and my…….now feels better. I used the tension gauge so I must have the right tension.
It is a confidence builder. I worked as an R.N. in peds for two years. I actually learned a lot more about writing being a nurse than an English major.

Good Luck,
Mark

[Dennis Peacock]

Ken: I went to the text file for the new book and copied this.

Silicon Steel Blades

One variation of the carbon steel blade is blade stock from Sweden which has a high silicon content. Silicon steel blades have a carbon content similar to C1074 spring steel. That is, it's carbon content ranges from .74-.79%. It's silicon (Si) content is high at around 1.5% whereas regular carbon steel has a silicon (Si) content of .16-.19%. The reason for high silicon content is its ability to tolerate heat. It is appropriately named "Friction" band and is used primarily for “friction sawing” when cutting metal at speeds of around 6,000-14,000 feet per minute. This technique is used to cut through different types of steel and compound materials. The material being cut is heated by the cutting action of the blades and softens in front of the cut. Even though the blade is not designed for woodworking it is aggressively marketed at a premium price. These blades have teeth in the 60 Rc range with a 30 Rc body. They are initially sharp and cut well in the beginning, but I don’t think that they are as durable as a high quality carbon steel blade. These blades are advertised as requiring less tension but there is not a good technical explanation for using less tension than usual.

Note to Ken G.
I was told by someone in the blade business that these blades have a tendency to stretch if too much tension is applied. I can not confirm that but that is one of the things I would like to test.

Hey Mark D.
I can tell you from experience that the Timberwolf Blades that I use will cut better and out last any other brand of BS blade of the same type and size. I used to use Lenox blades, but after I was pointed towards the Suffolk Machinery blades? I have never looked back.
I know there are other brands of BS blades out there, but I've tried 3 of them and I have settled on one that works long and cuts well for me without costing me an arm and a leg. Just my experiences with blade.

[Art Davis]

Okay, a newbie here---one who owns Mark's book as well as the one by Lonnie Bird, and have benefitted from both.

When I purchased my Grizzly G0555, I ordered Timberwolf blades. Tried their "flutter method," but all I could get was a heart flutter. Called them, and the rep there said, "Well, if it won't flutter, it doesn't really matter. Just set it up according to the tension adjustment on your saw." I have been doing that, and don't have any complaints. Resaw works fine, etc. (I have the six inch riser block and ordered the longer blades.) I do like the Timberwolf blades.

So, here's my question: how do those of you who have a lot of experience with the band saw adjust your blade tension? Frankly, after a long professional career of being a theoretician, here I find myself wanting the practical viewpoint. You can talk about stress, strain, Young's modulus, Hooke's law, etc, but it all boils down to a question of what will saw my wood the best. And I think that is an empirical issue, but one that seems to be "underaddressed" in the literature---including Mark's own fine book.

Anybody with any responses?

Thanks.

Art

[Pete Bradley]

Mark,

I think the answers may lie in the application of these gauges. Precision measurement is 5% about the tool and 95% about how it is used. It's really a science in itself, and few of us do enough to become experts.

My thoughts/questions:

1. Contact Starrett, explain who you are, and ask them about tension gauges. Starrett should be able to hook you up with someone who is expert not only with their gauge, but who can shed light on your questions.

2. Since the Carter gauge measures wheel load rather than measuring band strain directly, I expect it has to be calibrated somehow to account for band thickness and width (or c.s. area). How is this done?

3. When testing the Carter gauge, how did you determine the actual PSI at the band?

Pete

[Mark Duginske]

Good, then keep using them. I have used them and like them. I also like the Highland Woodslicer. Both give a good cut but I use the band saw a lot and I wish they would stay sharp longer. I think that for a serious hobbiest who isn't spending all day sawing they are a good choice. I think it is a good idea to experiment.

I now use a bimetal blade almost all the time because they last so long.
One of the experiments that I would like to do is on blades and test cut quality versus longevity. Also, there may be enough variation (speed, power)in saws that may make a difference in the performance of the blade.

[Mark Duginske]

Response to Pete Bradley

Your point is well taken. Aaron has a masters in metallurgical engineering so I assume he knows how to use the gauge.

I talked to the tech people at both Starrett and Lenox and was under whelmed by the response. No one could explain how the gauges we calibrated and/or tested. Also I talked to the engineer at Delta who says that now that he read the article he wants to do some test. One of the problems these days is that the "corporate memory” is short. The people who designed and built the 14” Delta
In 1933 or 34 in Milwaukee are long gone….. same with the Lenox and Starrett gauges. Getting good technical information these days can be a real challenge. The engineer at Carter was very knowledgeable and very helpful.

The Carter measures wheel load in pounds at the bottom of the tensioning rod. Aaron calculated the blade load to be 146 pounds
for a blade with that cross section at 15,000 psi. If you study the drawing you can see the blade in the corner of the one inch square.
15,000 psi is what both the blade and saw manufactures recommend for tension on a 14” band saw.

Mark D

[Mark Duginske]

No area of woodworking has more confusion among hobbyist woodworkers than blade tension. If you visit a professional woodworking shop or factory or a metalworking shop and look at the band saws they will be tensioned to the setting on the gauge. If you told these people who use saws all day long that the gauge was off or not accurate they would laugh at you. They are practical and the gauge has worked for them.

This whole tension controversy thing started about 18 years ago with the late Jim Cummin's article in Fine Woodworking Magazine which said that the gauge was erroneous, that the spring weakened, and the spring should be replaced with a stiffer spring.
HE WAS WRONG ON ALL ACCOUNTS, and knowledgeable practitioners disregarded the article. Cummins assumed that the Lenox gauge he was using was accurate not realizing the gauge was reading 15,000 psi in the 10,000 psi range. Which means that if you use that gauge you are overtensioning the saw by 50 percent. That article is the seed for the mistrust of tension gauges.

However, author’s and merchants have continued to pass on the false information without doing any research or testing. This wrong information (that the gauge on the saw is erroneous) is now accepted as fact in some circles and this poor quality information keeps getting quoted over and over.

I'm a fourth generation woodworker. Both my father and grandfather had businesses making patterns. I grew up in a shop with 3 different 14" Deltas and much bigger saws, all set at the gauge mark. That 14" Delta saw has been the standard of the industry for 75 year (often working 24 hours a day during WW2 in pattern shops). It astounds me that anyone who has used that 14" Delta saw a lot could believe Jim Cummins article that said the gauge is off, the spring is week and doesn't provide enough blade tension. That article is the seed for the mistrust of tension gauges.

USE THE GAUGE, AS THE BLADE DULLS YOU MAY WANT TO INCREASE THE SETTING. I USE THE GAUGE AT THE 1/2” SETTING FOR THE 1/2” BLADE BUT INCREASE THE SETTING TO 3/4” WHEN THE BLADE GETS DULL.

Don’t be afraid to experiment and change the tension .

Mark D

[David Rose]

Art,

I also started with TW blades. I couldn't get them to flutter (or to quit?) either. They were not steady, but never changed. This was on a Delta 14" US last model. This is my only rip saw and I ate those TW blades fast.

A fellow on the B. Pond found me a Lenox carbide blade at a good price. He convinced me to try it.

It took 1/32" or LESS planer cut to clean up the saw cut! I just used the minimal settings that TW recommended for their blades. That was about 3/8" blade if memory serves. It worked VERY well with no tracking adjustment. That may have been due to the teeth being wider than the band, but it was true.

Due to a "visitor" turning on the saw with no tension, I got a kink in the blade which I never could quite smooth out. I'm not sure that the new blade gives me quite the cut that the old one did, but it hasn't really been "tested" yet. I have tensioned it all the way up to 1/2" on the factory scale. I can tell little to no difference. I'm sure that the tension is fairly low. I have set the wheels as co-planer as feasible, added a riser block, use Cool Blocks adjusted well, changed the motor to 1HP with pulleys to up the speed to recommended, installed a brush, added half decent dust collection port, added a better table with tight insert, added link belt, squared up everything, basically I super tuned the saw. The saw will easily pass the nickel test.

This saw saw 6 TW blades in about 4 months before the carbide ones. The first carbide ran about 4 years before the accident. The new blade has seen little use. But if history repeats, tension will end up at around 3/8" with the factory spring. This is for resawing and ripping.

Oh, and I do release tension after each use. And I haven't broken a blade yet even on the 14" saw. One blade may not tell much, but we'll see with the second one.

David

Okay, a newbie here---one who owns Mark's book as well as the one by Lonnie Bird, and have benefitted from both.

When I purchased my Grizzly G0555, I ordered Timberwolf blades. Tried their "flutter method," but all I could get was a heart flutter. Called them, and the rep there said, "Well, if it won't flutter, it doesn't really matter. Just set it up according to the tension adjustment on your saw." I have been doing that, and don't have any complaints. Resaw works fine, etc. (I have the six inch riser block and ordered the longer blades.) I do like the Timberwolf blades.

So, here's my question: how do those of you who have a lot of experience with the band saw adjust your blade tension? Frankly, after a long professional career of being a theoretician, here I find myself wanting the practical viewpoint. You can talk about stress, strain, Young's modulus, Hooke's law, etc, but it all boils down to a question of what will saw my wood the best. And I think that is an empirical issue, but one that seems to be "underaddressed" in the literature---including Mark's own fine book.

Anybody with any responses?

Thanks.

Art

[Ken Garlock]

Your information on the silicon steel is the first write up I have seen. But. I will stick with my Lenox bi-metal blades.

[Mark Duginske]

Ken,

Please see the note to Dennis Peacock. There are a lot of good blades out there but I also have been using bimetal blades (Olsom MVP).

I got that info from the metal working field where that blade is used for friction sawing.

Regards,

Mark